.bigdiv{
    // width: 100vh;
    height: 100vh;
    background:url("../image/0016d1efa86d41e38e76801a7cd743c6wcupy21hvb.jpg") no-repeat;
    background-size: cover ;
    
}
.bigBox{
    width: 680px;
    height: 400px;
    background: #f3f3f3;
    position: fixed;
    left:50%;
    margin-left: -335px;
    top:50%;
    margin-top: -200px;
    border-radius: 10px;
    padding: 20px;
}
.logimg{
    width: 100px;
    height: 100px;
}